This invention relates to an intake valve for an engine and, more particularly, to a system and method for controlling the intake valve of an engine.
Internal combustion engines, such as a pushrod engine (overhead valve engine), for example, feature an intake valve that is coupled to a rotating cam through a valve train. Based on the rotation of the cam, the intake valve oscillates between an opening phase, during which an opening is formed to provide air (or an air/gas mixture) to a cylindrical cavity, and a closing phase, during which the opening is closed. In conventional internal combustion engines, the duration of the closing phase concludes based on a piston being positioned at a bottom portion of the cylindrical cavity. However, various operating parameters of the engine, such as a load, for example, determine an optimal duration of the closing phase, in order to optimize a performance characteristic of the engine, such as fuel efficiency and emissions, for example.
Conventional engine systems have been proposed to vary the duration of the closing phase during various operating phases of the engine (or upon the occurrence of one or more designated engine operating parameters), but these systems have several shortcomings. For example, these conventional engine systems do not facilitate a smooth transition between the various durations of the closed phase, as the operating parameters of the engine vary. Thus, optimization of the duration of the closing phase, based on the performance characteristics of the engine, is not often realized.